Refrigeration system



L. BUEHLER, JR

REFRIGERATION SYSTEM J Filed May 5, 19:57

Patented Dec. 213, E

, entree srrs leans RIEFBHGERATHQN SYSTEM Leon Euehler, lfn, Waynesboro, wa or to Trick Company, Waynesboro, Ea, a corpora-' tion of Pennsylvania Application May 3, 1937, Serial No. 140,534:

This invention relates to refrigeration broadly and more particularly to a refrigeration system employing moving parts requiring lubrication. The invention is particularly applicable to a refrigerating system employing a plurality of compressors operating in parallel.

v In compression type refrigerating systems, lubricating the working parts has been found to be a very important problem. Certain refrigerants sucr as, for example, methylchloride and dichlorodifiuoromethane are miscible with mineral oil lubricants, and as a consequence the refrigerant absorbs oil and the latter is carried with the refrigerant throughout the entire system. Certain other refrigerants are immiscible with oil, but no matter which type of refrigerant is used, in practice there occurs more or less, an accumulation of oil in various parts of the system.

With a refrigerating system employing more than one compressor, or a plurality of compressors, it becomes diflicult, if not impossible, to maintain an equalized circulation of lubricant throughout the system so that each compressor will receive its proportionate part of the lubricant, or to so apportion the oil returning to the compressors as to maintain the proper oil level in the crankcase of the latter.

The miscibility of refrigerants causes an accumulation of oil and refrigerant in the crankcase of an enclosed type compressor. degree of miscibility is a function of temperature and pressure, the quantity of refrigerant held by the oil in the crankcase is in practice variable. Consequently, evaporation, or release of refrigerant, from the oil does take place from time to time in the crankcase, with the result that oil is carried from the crankcase to the refrigerating system more rapidly than is the case when the system uses a refrigerant not miscible with oil. These conditions, therefore, make the oil level within the crankcase quite variable and extremely diiiicult to control whenever two or more such compressors are operated in parallel from a common refrigerating system. There are certain advantages in a system employing several compressors and utilizing a miscible refrigerant which make the use of such a system desirable.

In an efiort to maintain the proper oil level in the compressor crankcases, it has heretofore been proposed to connect equalizing oil lines therebetween both below and above the normal oil level. Practical experience has demonstrated, however, that the foregoing method does not solve the problem, nor have other prior known methods,

iii

Since the either in theory or practice, efiected a solution.

- Generally speaking it is an object of the present invention to provide means whereby adequate lubrication for the Working parts of a refrigerating system is insured. More specifically, the invention provides a simple and practical means for equalizing the crankcase oil levels of compressors in a multiple compressor system, and momentarily failing in this, to supply oil to the bearings of a' compressor or compressors not 10 having a supply of oil, thereby insuring a constant lubrication of wearing parts.

The foregoing and other objects and advantages of the invention will become apparent in view of the following description taken in con- 15 junction with the drawing, wherein:

Fig. 1.is a schematic diagram of a multiple compressor refrigerating system illustrating an application of the invention; and

Fi 2 is a view in section and elevation of an electric valve comprising part of the apparatus together with a wiring diagram therefor.

Referring to the drawing in detail, in the system illustrated only two compressors are shown, but it will be understood that any number thereof may be provided and arranged in parallel and the proper connections made therebetween. The compressors are indicated at it and Ma and are provided with discharge lines it and Ma feeding into a. common line 82 which leads to the con- 30 denser where the refrigerant is condensed or liquefied. The liquid refrigerant from the condenser passes through line it and expansion valve it to the evaporator, valve M functioning in a well known manner to reduce the pressure and temperature of the refrigerant. The low pressure or suction line for returning the gaseous refrigerant from the'evaporator is indicated at 85, this line leading to an oil separator which may be of any conventional construction and design 40 and at which point the oil is separated from the refrigerant, the latter returning to the compressor chambers through lines it and i611 where the gas is recompressed to repeat the cycle, and 45 the oil collected in the separator passing to the crankcases of the compressors through lines El? and E8. The oil separator may be located at any desired point or may in certain instances be omitted and the suction lines it and 16a connected directly to the crankcases of the compressors, where oil separation may ensue, this depending upon the type of compressor used.

The construction just described is illustrative of a conventional refrigerating cycle which is r cases l9 and i901. and at their opposite ends connect with oil pumps of conventional design, which pumps force the oil through lines 23 and 23a and 24 and 24a to the various hearings or moving parts of the compressors. No attempt has been made to .illustrate the particuar manner in which the oil I is fed to the'various bearings for the moving parts of the compressors, it being well understood that this may be accomplished by means of drilled openings in the compressor crank shaft, the

20 splash system, or in any other desired manner.

The oil-return system as well as the oiing system-proper, shown and described herein, are merely illustrative since there are numerous other types which are in use and may be adopted in 2 conjunction with the present invention without necessitating any material changes in the latter or without requiring changes other than those which fall within the province of those skilled in the art.

The lines 23 and 23a at their upper ends communicate or connect with one another through pipe 25, and said lines 23and 230. are provided with electrically operated valves 26 and 26a which may be closed when any one of the compressors ID or Ilia is shut down so as to prevent delivery of oil to the idle compressor or compressors from those which are in operation. The valves 26 and 26a may be of any preferred type, either automatically pr manually operable, one type of such 40 valve being illustrated in detail in Fig. 2. The

valve is provided with ports 21 and 28. A plunger or valve stem 29 is arranged to seat in port 27! and is actuated by a solenoid 30. M generally indicates electric supply lines which connect through 45 switch 32 with lead wires 33, the latter supplying currentto motor 34 which serves to drive one of the compressors Iii or Illa. The solenoid 3c is connected with the motor supply lines through wires35, so that when the switch 32 is closed, the

60: solenoid at will be energized to thereby raise the valve stem 2Q from its seat and open the line in which said valve may be installed.

" The valve illustrated is of the one-way type and as a consequence there is an individual valve for 55' each compressor. However, where there are only two compressors operating in parallel, a single two-way closing valve could be used, such valve interrupting communication between compressors when one is idle and the other in operation. Since" 50 the installation and operation of valves which are tight-closing against both directions of flow is of common knowledge to mechanics, it is not deemed necessary to show an example of such valve in the drawing.

The oil pumps are shown as of the gear type installed clear of the compressors. This'showing is made simply for: the sake of simplification and clarity, since-these pumps may be, and usually are, built into the compressor and driven from the latter. It should be noted, however, that the oil pumps operate only when their respective compressors are in operation, and while this may be readily accomplished by a direct gear connection with the compressor, it could also be accomplished by means of a separately driven motor arranged arcane to cut out automatically when its respective compressor ceases operation.

In operation, any oil that may be taken up by the circulating refrigerant collects in the oil separator, from whence it passes into the crankcases of the respective compressors through pipe lines H1 and it. When the compressors are in operation, the respective, valves 26 and 26a are open, and therefore communication is established between the oil lines 23 and 23a through pipe line 25. In each oil pressure system, circulation of oil normally ensues from the crankcase of the compressor through pipe 22, pipe 23 and pipe 24, to the bearings or moving parts of the compressor and back into the crankcase; and pipe line 25 constitutes a connection from the high pressure lubrication point of each compressor to the points of lubrication of the other compressors. Should, however, the oil level in any one of the compressors drop to a point where its oil pump is no longer supplied with oil or where the pump loses its prime, then the pressure would drop in that'particular system and a difierential in pressure ,would result which would cause the oil pump or pumps from the other compressors which are in operation to deliver part of their oil through-equalizing line to the compressor in which the supply hadrun low, the oil dropping into the crankcase and bringing the oil level up to normal.

As heretofore noted, the oil equalizing line 20 is preferably connected into the crankcases of the respective compressors at the normal oil level. The advantage in this is that when the oil level in any one of the crankcases attains a level above normal, the excess oil will flow to the crankcase or crankcases of the other compressor or compressors. However, oil cannot flow from one crankcase to another-when the level is below the nor-' mal. 7

It will be seen that the equalizing action is highly efiective. Any tendency, for the'crankcase of a compressor to run short of oilis counteracted since the oil cannot be forced from a compressor where the level is below the normal level to one of the other compressors through the equalizing line 25 as this line is connected into the system at the normal level, and if the oil level in any compressor drops to a point where the oil pump loses its prime, oil will immediately be delivered from one of the, other compressors.

Furthermore, if one of the compressors loses its charge of oil, the bearings will not run dry but will be kept lubricated by the lubricating system of the other compressor or compressors.

While the improved-oil equalizing apparatus of the present invention is primarily adapted for use with a refrigeration system, and is constructed to coact with such systems, there may be other types of installations to which it could be applied without necessitating such changes as would involve inventive ingenuity; and I do not therefore restriotmyself to the particular installation shown. in the drawing and described in the specification but only insofar as may fall within'the bounds \of the appended claims.

I claim:

1. In a refrigerating system, a plurality of co acting compressors, an oil pressure lubricating system for each compressor including a crankcase and means for causing acirculation of oil from the crankcase to the-moving parts of the compressor and back to the crankcase, and an equalizing conduit communicating the oil pressure system of one compressor with the oil presizing conduit communicating the oil pressure sysgra ers sure system of another, said conduit being connected from the high pressure lubricating point of the one compressor to the points of lubrication of the other compressor.

2. In a refrigerating system, a plurality of coacting compressors, a lubricating system for each compressor including a crankcase and pressure means for causing a forced circulation of oil from said crankcase to the moving parts of the compressor-and back to the crankcase, an equaltems of the respective compressors, and another oil equilizing conduit communicating the crankcases of the respective compressors.

3. In a refrigerating system, a plurality of coacting compressors, conduits forming a closed path for the refrigerating cycle, pressure lubricating systems for the respective compressors,

means for returning oil taken up by the refrigerant during the refrigerating cycle to the lubricating systems, and means for automatically equalizing the oil pressures in the respective'lubricating systems.

4.- In a refrigerating system, a plurality of compressors operating in parallel having enclosed crankcases, conduits forming a closed path forthe refrigerating cycle, pressure lubricating systems for the respective compressors, means for pressors operating in parallel having enclosed crankcases, conduits forming a closed path for the refrigerating cycle, pressure lubricating systems for the respective compressors, means for returning oil taken up by the refrigerant during the refrigerating cycle to the respective crank- "cases, and equalizing conduits communicating the pressure systems and also said crankcases, the

conduits communicating the crankcases connecting into the latter adjacent the normal oil level of the oil supply in the crankcase.

6. In a refrigerating system, a plurality of compressors arranged for parallel operation, a condenser, an evaporator, connecting conduits therefor, pressure lubricating systems for the respective compressors, means for returning oil taken up by the refrigerant during its passage through.

' the refrigerating system to the lubricating systems, conduit means connecting said lubricating systems with each other, and valve means in said conduit means, so associated with each compressor, as to prevent communication, by way of said conduit means, between one lubricating system and the remainder ofsaid lubricating systems when the compressor corresponding to the said one lubricating system is idle and to permit such communication when the said compressor is operated.

7. In a refrigerating system, a plurality of compressors operating in parallel, conduits forming a closed path for the refrigerating cycle, pressure lubricating systems for the respective compressors including an oil pump, equalizing conduits communicating the respective lubricating systems at the pump discharge.

8. In a refrigerating system, a plurality of compressors operating in parallel and having enclosed crankcases, conduits forming a closed path for the refrigerating cycle, pressure lubricating systems for the respective compressors including an oil pump operating to take the oil supply from the crankcase and circulate the oil under pressure to the moving parts of the compressor and back to the crankcase, equalizing conduits interconnecting the respective lubricating systems at thepoint of the pump discharge, and further equalizing conduits intercommunicating the respective crankcases.

9. In a refrigerating system, a plurality of compressors operating in parallel and having enclosed crankcases, conduits forming a closed path for the refrigerating cycle, pressure lubricating systems for the respective compressors including an oil pump arranged to take the oil supply from the crankcase and circulate the oil under pressure to the moving parts of the compressor and return it to the crankcase, means for returning oil taken up by the refrigerant during 'the refrigerating cycle to the respective crankcases, an equalizing conduit communicating each two compressors at the point of the pump discharge whereby in case of a drop in pressure in any of the respective lubricating systems oil under pressure will be delivered from the system or systems of the other compressor or compressors, and other oil equalizing conduits communicating the respective crankcases, said latter conduits being connected into the crankcase adjacent the normal oil level therein.

10. In a refrigerating system, a condenser, an evaporator and two or more compressors arranged in parallel operation, a lubricant and a refrigerant, the lubricant and the refrigerant being of such types that one may be absorbed in the other, a pressure lubricating system for each compressor, conduit means connecting said lubricating systems,-valve means in said conduit means, said valve means being so associated with each compressor as to prevent communication, by way of said conduit means, between one lubricating system and the other systems when the compressor correspondingto thesaid one lubricatin system is idle and to permit such communication when the said compressor is operating, an oil sump for each compressor, conduit means connecting said oil sumps, the inlet from each oil sump to'said oil sump conduit connecting means arranged to be at the normal level or below said normal level of lubricant in each oil sump, a vapor space above the oil sump in each compressor, and conduit means connecting said vapor spaces, an oil separator at the outlet -of the evaporator for returning oil in the refrigerant leaving the evaporator to the said oil sumps.

11. In a refrigeration system, a plurality of co-acting compressors, pressure lubricating systems for the respective compressors, an equalizing conduit communicating one lubricating system with another, means in addition to said conduit to eficct the flow of lubricant from one lufor efiecting the transfer oflubricant to said unit from another unit.

13. The combination with two co--acting machines utilizing a lubricant, a dynamic lubricating system for each machine,.conduit means connecting saidsystems, means in addition to said conduit means and associated with said systems and said conduit means for supplying lubricant is from one of said systems to the other system in response to the pressure difierence between said systems.

14. In combination with two co-acting machines each of which utilizes a lubricant, a pressure lubricating system for each machine, conduit means connecting said systems, means in addition to said conduit means and associated with said systems and said conduit means and responsive to a drop in lubricant pressure intone of said systemsfor supplying lubricant from the second system to said first mentioned system.

15. In combination with a' plurality of coacting machines each of which utilizes a lubricant; a pressure lubricating system for each machine, conduit means connecting said systems, means associated with said systems, and said conduit means for automatically supplying lubricant from one or moreof said systems to another system responsive to a drop in lubricant pressure in said other system, a lubricant sump associated with each machine, and second conspaces.

duit means connecting said lubricant sumps, said second conduit means having inlets from each lubricant sump at or below the normal level of lubricant in each of said sumps.

16. In combination with a plurality of co? acting machines each of which utilizes a lubricant, a pressure lubricating system for each ma means connecting said lubricant sumps, said second conduit means having inlets from each lubricant sump at or below the normal level of lubricantin each of said sumps, a space above each lubricant sump associated with said machines, and third conduit means connecting said go 

